Poured concrete foundations for buildings have been used for many years. Pier blocks can be used as one part of a concrete foundation for buildings. Pier blocks are used to support columns or other weight bearing vertical members of a structure.
Typically pier blocks are constructed in two stages. The first stage is the preparation of a form that is the desired size and shape of the pier block, and the second stage is pouring concrete into the form to make the pier block.
One type of form used for pouring concrete pier blocks is constructed from wood. Such forms are usually constructed on the building site and making these forms can consume a significant amount of time. After the concrete inside these forms has set, they must be removed from the pier block so that the pier block can be inspected and so as not to attract insects. The wood used for these forms is usually contaminated with concrete and thus is generally unsuitable for use elsewhere in the building.
Consequently, when constructing pier blocks using conventional wood forms, there is a significant amount of labor required for constructing the forms and stripping the forms after the concrete has set, and there is also a high wastage of the form material once it is stripped from the concrete. The resulting expense from the required labor and the wastage can be quite sizable on large construction projects.
Cardboard forms have been used for pier blocks in an attempt to reduce wastage of wood and the amount of labor required. Typical embodiments of cardboard forms can include cardboard tubes and box or rectangular forms made from cardboard. While cardboard forms can reduce wastage and the amount of labor required, this reduction comes with significant drawbacks.
Because some building codes require that forms be inspected before concrete is poured into them, forms are typically put in place before the concrete arrives on the construction site. In some cases, the forms can remain in place for days before concrete is poured into them. While leaving cardboard forms in place on dry soil in dry weather conditions has no adverse effect on such forms, damp ground, dew, and rain can severely degrade the forms and adversely affect their ability to hold wet concrete. Additionally, commercially available cardboard forms do not have any provisions for holding reinforcing bars within the interior of the form and the forms are difficult to remove once the concrete has set.
Because cardboard is not rigid, the walls of the form tend to bulge outward when concrete is poured into the form. If the form is damp, the bulging deformation can be uneven or non uniform and the pier block will have an non uniform shape and non uniform coverage of any reinforcing bars placed in the form.
Another type of bulging can occur where the top of the form bulges out further than the bottom of the form causing the surface area at the top of the pier block to be greater than the surface area of the bottom of the block, thereby increasing the volume of concrete required to construct the pier block. When this type of bulging occurs, the bulged areas of the pier block bear little weight of any structure resting on the pier block because they are not in contact with the ground.
In some locations, the cardboard can attract insects such as termites that could ultimately infest the building. To prevent such insect problems, many local building codes require all cardboard to be removed from pier blocks. Oftentimes large quantities of cardboard remain stuck to pier blocks after the form has been stripped off and significant labor is required to remove it. Thus, while cardboard forms do have some advantages over conventional wood forms, wastage caused by having to replace forms ruined by moisture and the labor required to remove all cardboard from the finished pier blocks can result in unanticipated expenses.
As more and more governments update their respective building codes, the number of locations that require pier blocks to be reinforced with steel is growing. Steel reinforcement generally takes the form of reinforcing bars that are placed in the form in such a manner that the wet concrete completely covers the reinforcing bars. When using wood or cardboard forms, some type of stand is generally required to hold the reinforcing bars in place while the concrete is being poured. Placing the stand so that it will hold the reinforcing bars in the desired location within the form requires additional labor and some degree of skill.
Thus, there exists a need for a form used for the construction of concrete pier blocks that is easy to assemble, resistant to the effects of moisture, capable of holding reinforcing bars in a desired location, and does not need to be removed from the pier blocks once they have set. Such forms that are light weight, collapsible, easily stored and easily transported would be significant improvements over the prior art.